Hello Group, Picked up my 1989 Mondial t cab today. Finished all the work and was enjoying driving it. After some spirited driving, the Slow Down 5/8 light came on. Then it went off, then came back on again. I had both Catalytic converters repacked/cored by a reputable source and New O2 sensors were placed at that time (4-5 months ago). Any thoughts on what the issue could be??
hmmm...very strange ... some things to consider... 1. if the cat is getting hot, that side of the engine may not be firing - but you'll notice this - is it running rough? 2. Check the electrical connection at the top of the engine frame (it's on the left side) Some times that can get disconnected 3. Might be the temp circuit - it's in the truck behind the felt drop down trunk behind the drop-down. It looks like a rectangular box. Basically you should to confirm if the cat is really hot or is it's a electrical gremlin... if the cat is getting hot then you know something went awry in the refurb, if the cat is not glowing (best to check in the dark) then it might be the temp sensor... -paul
. the engine is running rich most likely missed firing can cause that too. but if some cyl are not firing, you will notice.
The slow down light is really a heat sensor attached to a computer. Since each bank of cylinders is independently fueled and ignitioned, Ferrari has these sensors as the engine could run with one bank failing, while being pumped with raw fuel, which would pool in the cat and go on fire. The sensor is saying the temp in the cat is getting too high, as a result of excess fuel. Could be a distributor cap or coil or plug wire causing a miss that allows unburned fuel. But you should notice the car not running smoothly if this is the case. Also why the comment of the mixture being rich could be a cause of an intermittent light going on. If the cat is overheating, it can glow red hot. So if the light is on after your drive, leave it out of your garage after the drive, shut down and let it cool down, as you don't want a car to be a fire risk in your garage! In any event it would be useful to get one of the infrared laser temp guns and aim at each cat and see if they are similar temps, as part of the diagnosis. But for all the drama potential, its just as likely the sensor is coated in some carbon, and or the connection to the trunk cat computer is oxidized, sending some erroneous resistance signal. I would find the computer, clean and put deoxit on the connection. Then remove the sensor probe in the cat, lightly clean it off with a brass wire bush, and reinstall. If it still lights off, but the car runs fine, sensor might be shot (I think there is also a simple resistence test with an ohm meter but I cant recall). Or the computer box failed. And of course the prices for these things are high, so not the kind of things you just replace without a bit of diagnosis first. If indeed the sensors are working, then it is flagging some incomplete combustion issues that do need to be solved. I had the intermittent light on and flicker, and did as I noted, and all has been fine for years since. So hopefully you just have an age related electrical glitch too.
Does the engine run poorly when the light comes on, or does the engine appear to be running normally?
Intermittent light? Could be a loose wire. Try a cold start. If the light comes on when the engine is cold, then it must not be an overheated cat. It is either a loose wire, or bad sender.
H had a problem with the slow down lights coming on 4 years ago, never came on since after my fix: Re-post: I have been noticing my Slow Down light flickers on and off about 30 mins into driving in the city, I take it to the highway its its fine. The light finally stayed on for a minute, I pulled over and looked at the cat, nothing all looked normal and no loss of power. Came back home and lifted the rear in my garage, examined the thermocouple wire, notice it was rubbing against the sharp edge of the cat right to the bone wire. Unscrewed the thermocouple, got some thermo tape and began to wrap the wire all the way up to where it goes into the trunk and ECU. Not sure if it will be a permanent fix, but for now it works and I know its in a better condition than when I started. Oxygen sensor seems okay for now. Will check the sparkplugs and distrib/rotors next for a good cleaning or replacement. Well, at least it gives me an excuse to monkey around in the garage when my wife wants to go out shopping! -Mike
I'm not sure if the T model has a thermocouple wire to the ECU, believe it does but on the 3.2, it looks like this and goes right into the cat-converter. Inspect that wire for cuts and defects to where it plugs into the ECU. Best Image Unavailable, Please Login
Not as of yet. Today I had a look under the car. The thermocouple wires from the CATS to the ECU were hanging down. The left one was in contact with the CAT- perhaps this caused the reading? I took up the slack into the trunk (where the ECU's are) and I'll see if that makes a difference. I'll give it another spirited drive when the weather is nice again! If the light comes on, I'll have the temps at the CATS checked.
